Experimental infectious challenge in pigs leads to elevated fecal calprotectin levels following colitis, but not enteritis

Abstract

Background Fecal calprotectin is largely applied as a non-invasive intestinal inflammation biomarker in human medicine. Previous studies in pigs investigated the levels of fecal calprotectin in healthy animals only. Thus, there is a knowledge gap regarding its application during infectious diarrhea. This study investigated the usefulness of fecal calprotectin as a biomarker of intestinal inflammation in Brachyspira hyodysenteriae and Salmonella Typhimurium infected pigs. Results Fecal samples from pigs with colitis (n = 18) were collected from animals experimentally inoculated with B. hyodysenteriae (n = 8) or from sham-inoculated controls (n = 3). Fecal samples from pigs with enteritis (n = 14) were collected from animals inoculated with Salmonella enterica serovar Typhimurium (n = 8) or from sham-inoculated controls (n = 4). For both groups, fecal samples were scored as: 0 = normal; 1 = soft, wet cement; 2 = watery feces; 3 = mucoid diarrhea; and 4 = bloody diarrhea. Fecal calprotectin levels were assayed using a sandwich ELISA, a turbidimetric immunoassay and a point-of-care dipstick test. Fecal calprotectin levels were greater in colitis samples scoring 4 versus ≤ 4 using ELISA, and in feces scoring 3 and 4 versus ≤ 1 using immunoturbidimetry (P < 0.05). No differences were found in calprotectin concentration among fecal scores for enteritis samples, regardless of the assay used. All samples were found below detection limits using the dipstick method. Conclusions Fecal calprotectin levels are increased following the development of colitis, but do not significantly change due to enteritis. While practical, the use of commercially available human kits present sensitivity limitations. Further studies are needed to validate the field application of calprotectin as a marker of intestinal inflammation.

Measurement of Calprotectin (S100A8/A9) in the Saliva of Pigs: Validation Data of A Commercially Available Automated Assay and Changes in Sepsis, Inflammation, and Stress

“…The second modification was the calibration of this assay with Calibrator B, which consists in a pooled saliva sample with a known concentration of CALP, in order to reduce the possible matrix effect. Overall, the modified assay of our study was precise and linear in saliva, being in line with the previous report in which this assay could detect CALP in the faeces of pigs [ 6 ].…”

“…This assay was selected for validation because it has also been previously described to measure CALP in pig faeces, and therefore it has already been shown to be able to detect CALP in this species. Furthermore, it is an automated assay suitable for veterinary clinical pathology laboratories [ 6 ]. This assay uses polystyrene nanoparticles coated with polyclonal antibodies, which form complexes with CALP that can be detected by light absorbance using automated clinical chemistry analysers, therefore it is a rapid assay allowing high sample throughput.…”

“…However, it can also be quantified in saliva, where CALP has been reported to be increased in patients with active inflammatory bowel disease, suggesting that intestinal inflammation leads to increases in CALP in this sample type [ 5 ]. In pigs, CALP protein levels have been measured in faeces, increasing in animals with colitis [ 6 , 7 , 8 ]. In addition, variations in gene expression for calprotectin have also been found in the ileum after oral vaccination against E. coli [ 9 ].…”

Effect of chronic and acute enterotoxigenic E. coli challenge on growth performance, intestinal inflammation, microbiome, and metabolome of weaned piglets

“…Increased concentrations of fecal calprotectin have been positively correlated with the histological activity of inflammatory bowel disease in humans 30 , and serve as a marker of neutrophilic intestinal inflammation 31 . Fecal calprotectin has also been suggested as a noninvasive marker of intestinal inflammation in swine 32 , however additional study is necessary. Past studies have investigated calprotectin in swine plasma, intestinal lumen, and jejunal mucosa, all of which were found to be correlated with bacterial infection 33 , 34 .…”

Morphological Assessment and Biomarkers of Low-Grade, Chronic Intestinal Inflammation in Production Animals

“…Fecal and circulating levels of calprotectin have been used as a biomarker to track the gut inflammatory activity in human [ 78 , 79 , 80 , 81 , 82 , 83 ] and canine [ 74 , 84 , 85 , 86 ] patients with chronic enteropathies. In swine, the biomarker has been applied to evaluate the intestinal disruption by pathogenic enterobacteria and their toxins [ 87 , 88 , 89 , 90 , 91 , 92 ], but also to evaluate the positive effects of dietary supplementations on the intestinal inflammation and integrity [ 92 , 93 , 94 ]. Studies in human health show that the blood levels of calprotectin increase in response to diverse conditions involving tissue damage and inflammation, not exclusively in the intestine [ 72 , 95 ].…”